Cast-in boss for feature attachment on steel casting

ABSTRACT

A fastening system and method adapted for use on materials having poor machining characteristics, which provides an attachment feature for a component or an assembly. The attachment feature includes a mount having a boss defining a boss recess and a fastening surface. A first fastener is affixed to the fastening surface. A second fastener is received through an auxiliary feature and engages the first fastener to affix the auxiliary feature to the component. The boss recess may accommodate a portion of the second fastener.

FIELD OF THE INVENTION

[0001] The present invention relates to a fastening system for mounting auxiliary features to a component. More specifically, the present invention relates to a fastening system for mounting an auxiliary feature to a mount defining a boss, a fastening surface and a boss recess. The fastener and boss recess are configured to receive another fastener to affix the auxiliary feature.

BACKGROUND OF THE INVENTION

[0002] Auxiliary features are often mounted to components during the manufacture of products, including the manufacture of automobiles. Such manufacturing processes often require the creation of many sub-assemblies and installation of those sub-assemblies into the final product. This allows sub-assemblies to be more ergonomically and efficiently manufactured and installed into final products, thereby reducing manufacture cost and time.

[0003] It can be difficult to mount auxiliary features to components during the manufacturing process. Such difficulties can arise with the placement and the space available for mounting fixtures for the auxiliary features. Additionally, material thickness and composition may inhibit the integration of mounting fixtures with components. Certain manufacturing methods may also interfere with the integration of mounting fixtures, owing typically to manufacturing imperfections such as mold seams or flashings, among other defects.

[0004] In one example, an exhaust manifold requires the attachment of at least one auxiliary feature, such as a heat shield. Manufacturers are typically required to incorporate mounting fixtures into the design of the exhaust manifold to accommodate one or more fixtures of the heat shield. One method uses preformed bosses on the surface of the exhaust manifold. These bosses are threaded to receive a fastener for mounting the heat shield to the exhaust manifold.

[0005] Also, demands for increased efficiency and performance have motivated designers to improve engine components such as the exhaust manifold. For increased performance, exhaust manifolds are increasingly cast from steel. While steel manifolds, and more specifically stainless-steel manifolds, provide desired results from an operative perspective, the mounting of auxiliary features such as heat shields is much more difficult due to certain material properties of steel, such as poor machining characteristics.

SUMMARY OF THE INVENTION

[0006] The present invention provides a fastening system for a component. The fastening system comprises a mount defining a boss on the exterior surface of a component having a boss recess, a fastening surface and a fastener. This configuration allows an auxiliary feature to be mounted to the component without the machining of threads. The present invention also provides a method for creating a mounting fixture for a component and a method for affixing an auxiliary feature.

[0007] In a first aspect, the present invention provides an exhaust manifold adapted for mounting an auxiliary feature. The exhaust manifold includes a manifold body having an exterior surface and an interior surface. A mount is extending from the exterior surface and includes a boss defining a boss recess and a fastening surface. A first fastener is affixed to the fastening surface and includes a fastener opening aligned with the boss. The fastener opening is adapted to receive a second fastener for affixing the auxiliary feature.

[0008] In a second aspect, the present invention provides a fastening system including a component having a mount. The mount includes a boss defining a boss recess and a fastening surface. A first fastener is affixed to the fastening surface and includes a fastener opening coaxially aligned with the boss recess. An auxiliary feature is provided having an aperture adapted for mounting to the component. A second fastener is received through the aperture and engages the first fastener, whereby the auxiliary feature is affixed to the component.

[0009] In a third aspect, the present invention provides a method for creating an attachment feature on an exterior surface of an engine manifold. The method includes: a) forming a boss on the exterior surface of the engine manifold; b) forming a boss recess through the boss; c) forming a fastening surface on the boss; d) providing a first fastener having an opening; e) positioning the fastening opening coaxially with the boss recess; and f) affixing the first fastener to the fastener surface.

[0010] In a fourth aspect, the present invention provides a method for mounting an auxiliary feature on an exterior surface of a component. The method including: a) providing a mount on the exterior surface of the component, the mount including: i) a boss defining a boss recess and a fastening surface; ii) a first fastener having an opening aligned with the boss recess, the first fastener affixed to the fastening surface; and b) mounting the auxiliary feature to the component with a second fastener disposed through the auxiliary feature and engaging the first fastener.

[0011] Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limited the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

[0013]FIG. 1 is a perspective view of the fastening system of the present invention;

[0014]FIG. 2 is an exploded perspective of a first configuration of the fastening system of the present invention;

[0015]FIG. 3 is an exploded perspective of a second configuration of the fastening system of the present invention; and

[0016]FIG. 4 is a cross-sectional view of the first configuration of the fastening system of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The following description of the preferred embodiment is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.

[0018] Referring to FIG. 1, a component 10, such as an exhaust manifold, is configured with an exterior surface 12, an interior surface 14, and a flow path 16 defined by the interior surface 14. Preferably, the component 10 is formed from steel or stainless-steel through a process such as forging or casting; however, other materials are suitable such as iron, aluminum, polymers, etc., likewise, other forming methods are also suitable. Referring to FIGS. 1 and 2, the component 10 is further configured with one or more mounts 18 extending away from the exterior surface 12. Each mount 18 includes a boss 22 having a generally flat fastening surface 20 and a boss recess 28 extending axially therethrough.

[0019] Referring to FIGS. 1, 2 and 4, a first configuration of a mount 18 is illustrated having a generally cylindrical shape. The mount 18 is defined by a boss 22 having an annular exterior wall 24, a fastening surface 20, and a boss recess 28 disposed generally perpendicular to the fastening surface 20. Typically, the mount 18 is located in a substantially flat portion of the component 10, though other locations are possible. The mount 18 may be formed during the casting of the component 10 or, alternatively or in conjunction with, it may be formed using a machining process.

[0020] Referring to FIGS. 2 and 4, a first fastener 26, such as a nut having an opening 27 and internal threads, is affixed to the fastening surface 20. The opening 27 of the first fastener 26 is positioned coaxially with the boss recess 28. The boss recess 28 is configured such that it can receive a portion of another fastener, such as a bolt, projecting through the first fastener 26. The first fastener 26 may be affixed to the fastening surface 20 by a weld 29, adhesive, press-fit, etc.

[0021] As illustrated in FIG. 1, the first fastener 26 may be an alternate first fastener 30, which may be better suited to affix a specific auxiliary component, increase durability of the affixation, or increase the mounting surface area. Likewise, as illustrated in FIGS. 2 and 4, the first fastener 26 may be configured with additional features to improve the mounting and affixation to the fastener surface. A first feature includes a skirted portion 40 extending radially outward from the first fastener 26. The skirted portion 40 increases the affixing surface area between the first fastener 26 and the fastening surface 20 thereby increasing the strength of the mounting fixture. Likewise, in a second feature, an axially extending lip 42 is projecting from the first fastener 26, which increases the strength of the mounting fixture by providing resistance to planar movement of the first fastener 26 across the fastening surface 20 and providing addition affixing surface area if desired. Also, the extending lip 42 may be used as a locating devise during installation onto the fastening surface 20.

[0022] Referring to FIG. 4, with the first fastener 26 affixed to the fastening surface 20, an auxiliary feature 32, such as a heat shield, having an aperture 33 receives a second fastener 34, which affixes the auxiliary feature 32 to the component 10 via engagement with the first fastener 26. As shown, the second fastener 34 is a bolt having an elongated shank with external threads. Again, as illustrated in FIGS. 2 and 4, the second fastener 34 may also include strengthening features such as an outwardly extending skirted portion 44. The skirted portion 44 is configured to distribute the fastening load over a larger surface area of the auxiliary feature 32, which reduces the potential stress to the auxiliary feature 32 and second fastener 34. Because the boss recess 28 has a larger diameter than the opening 27 of the first fastener 26, any portion of the second fastener 34 extending beyond the first fastener 26 is accommodated by the boss recess 28. The boss recess 28 does not secure the second fastener 34, and thus is not machined or otherwise threaded to receive the second fastener 34.

[0023] Referring to FIGS. 1 and 3, in a second configuration a mount 18′ is configured with two outwardly projecting legs 36. The mount 18′ is defined by a boss 22′ having the outwardly projecting legs 36, a fastening surface 20′, and a boss recess 28′ disposed generally perpendicular to the fastening surface 20′, thereby providing a generally U-shaped profile. While this configuration may be used anywhere on component 10, it is particularly useful on an uneven portion of the component 10, or along a manufacturing seam 38.

[0024] As with the fastening surface 20 of the conical shaped mount 18, the present fastening surface 20′ may be machined after manufacturing the component 10. This second configuration reduces any interference caused by flashings, mold parting lines, or other excess material resulting from the casting process. Additionally, it is foreseeable that more than two outwardly projecting legs 36 may be used to create the mount 18′ and define the boss 22′, thereby increasing the surface area of the fastening surface 20′.

[0025] Referring to FIG. 3, as with the first configuration, a first fastener 26 having an opening 27 and internal threads is affixed to the fastening surface 20′ created by the outwardly projecting legs 36. The opening 27 of the first fastener 26 is positioned coaxially with the boss recess 28′, which is configured to receive a portion of a second fastener 34 projecting through the first fastener 26, similar to that describe above for the first configuration. Further, the fastener 26 is secured to the fastening surface 20′ of the mount 18′ in a manner similar to that described for the first configuration. Likewise, the alternate first fastener 30 and additional fastening features such as a skirted portion 40 and extending lip 42 used in the first configuration may also be used for the present configuration.

[0026] Referring to FIGS. 1 and 2, the present invention provides a method for creating an attachment feature on the exterior surface 12 of a component 10, such as an engine manifold, for an auxiliary feature 32. The method comprising the step of first forming a mount 18 having a boss 22 defining a fastening surface 20 and a boss recess 28 on the exterior surface 12 of the engine manifold or component 10. Any of the mounts 18, including the boss 22, fastening surface 20, or boss recess 28 may be formed during the manufacturing of the component 10 or through machining techniques or a combination thereof. A first fastener 26, such as a nut, is provided and includes an opening 27 and internal threads. The opening 27 of the first fastener 26 is positioned coaxially with the boss recess 28. Once positioned, the first fastener 26 is affixed to the fastening surface 20. At this point, the component 10 is prepared to mount an auxiliary feature 32 to the first fastener 26 using a second fastener 34, wherein any portion of the second fastener 34 extending through the first fastener 26 is accommodated by the boss recess 28.

[0027] Referring to FIGS. 1 and 2, the present invention also includes a method for mounting an auxiliary feature 32 on an exterior surface 12 of a component 10. The method includes providing a mount 18 on the exterior surface 12 of a component 10. The mount includes: i) a boss defining a fastening surface 20 and boss recess 28 whereby the boss 22 is configured to receive a second fastener 34 and ii) a first fastener 26 having an opening 27 coaxially aligned with the boss recess 28 and affixed to the fastening surface 20. An auxiliary feature 32 is mounted to the first fastener 26 with a second fastener 34, which is disposed through the auxiliary feature and engaged with the first fastener and selectively in the boss 22. All the techniques and manufacturing methods used in the method for creating an attachment feature on the exterior surface 12 of a component 10, such as an engine manifold, for an auxiliary feature 32 can also be used in the method for mounting auxiliary features.

[0028] The present invention demonstrates several systems and methods in which a material having poor machining characteristics, such as steel or stainless-steel, can be configured with a threaded portion to facilitate affixation of auxiliary features. While the fastening system above was demonstrated using an exhaust manifold, it is foreseeable that this system and method can be used for any material regardless of its machining characteristics. Likewise, the present invention may also be used with any material that is amenable to welding or adhesion for the attachment of an auxiliary feature or to a component.

[0029] The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention. 

What is claimed is:
 1. An exhaust manifold for mounting an auxiliary feature, the exhaust manifold comprising: a manifold body having an exterior surface and an interior surface; a mount extending from said exterior surface, said mount including a boss defining a boss recess and a fastening surface; a first fastener affixed to said fastening surface and including a fastener opening, said fastener opening aligned with said boss recess and adapted to receive a second fastener for affixing the auxiliary feature.
 2. The exhaust manifold of claim 1, further comprising a weld affixing said first fastener to said fastening surface.
 3. The exhaust manifold of claim 1, wherein said boss is generally conical in shape.
 4. The exhaust manifold of claim 3, wherein said boss recess is an annular bore through said boss.
 5. The exhaust manifold of claim 1, wherein said boss includes two outwardly extending legs.
 6. The exhaust manifold of claim 5, wherein said boss recess includes a gap between said two outwardly extending legs.
 7. The exhaust manifold of claim 1, wherein said boss includes steel.
 8. A fastening system comprising: a component having a mount, said mount including a boss defining a boss recess and a fastening surface; a first fastener affixed to said fastening surface and including a fastener opening aligned with said boss recess; an auxiliary feature having an aperture adapted for mounting to said component; and a second fastener received through said aperture and engaging said first fastener, whereby said auxiliary feature is affixed to said component.
 9. The fastening system of claim 8, further comprising a weld affixing said first fastener to said fastening surface.
 10. The fastening system of claim 8, wherein said boss is generally conical in shape.
 11. The fastening system of claim 10, wherein said boss recess includes an annular bore through said boss.
 12. The fastening system of claim 8, wherein said boss includes two outwardly extending legs.
 13. The fastening system of claim 12, wherein said boss recess includes a gap between said two outwardly extending legs.
 14. The fastening system of claim 8, wherein said boss includes steel.
 15. A method for creating an attachment feature on the exterior surface of an engine manifold, the method comprising the steps of: a) forming a boss on said exterior surface of said engine manifold; b) forming a boss recess through said boss; c) forming a fastener surface on said boss; d) providing a first fastener having a opening; e) positioning said opening coaxially with said boss recess; and f) affixing said first fastener to said fastener surface.
 16. The method of claim 15, further comprising the step of mounting an auxiliary feature to said first fastener using a second fastener.
 17. The method of claim 15, further comprising the step of machining the fastener surface.
 18. The method of claim 15, wherein said steps forming of said boss, boss recess and said fastening surface is performed when manufacturing the engine manifold.
 19. The method of claim 15, wherein said step of affixing said first fastener to said fastener surface includes welding.
 20. A method for mounting an auxiliary feature on an exterior surface of a component, the method comprising the steps of: a) providing a mount on said exterior surface of the component, said mount including: i) a boss defining a boss recess and a fastening surface; ii) a first fastener having an opening aligned with said boss recess, said first fastener affixed to said fastening surface; and b) mounting the auxiliary feature to the component with a second fastener disposed through the auxiliary feature and engaging said first fastener.
 21. The method of claim 20, further comprising the step of machining the fastener surface. 